System and method for mounting integrated circuits onto printed circuit boards, and testing method

ABSTRACT

An integrated circuit (IC) device is mounted onto a printed circuit board (PCB) by inducing a magnetic field of a selected strength at the surface of the PCB to temporarily hold the IC device onto the PCB. The IC device is provided with magnetic material which is attracted by the magnetic field. The magnetic field is maintained while the IC device and PCB are tested, and then subsequently during soldering when the IC device is permanently bonded to the PCB.

TECHNICAL FIELD

[0001] This invention relates to a system and method for mountingintegrated circuits onto printed circuit boards. This invention alsorelates to a method for testing integrated circuits and printed circuitboards.

BACKGROUND OF THE INVENTION

[0002] Electronic circuit boards for computers and other devicestypically consist of many integrated circuits mounted on a printedcircuit board (PCB). Individual integrated circuit (IC) packages have asemiconductor chip or die enclosed within a protective plastic package.A lead frame consisting of multiple conductive leads provide theelectrical interconnect between the enclosed semiconductor chip andcomponents exterior to the plastic package.

[0003] The PCB has many conductive traces arranged on its surfaceaccording to a selected pattern for efficiently transferring electronicsignals across the board to and from individual IC packages. The traceson the PCB have terminal locations or bonding sites which define thelocations that specific IC packages are to be located. As the IC packageis being mounted to the PCB, the conductive leads of the IC package arealigned with corresponding bonding sites on the PCB. The conductiveleads are then soldered to the corresponding bonding sites topermanently mount the IC package to the PCB.

[0004] One significant problem in the mounting process is how toinitially position the IC packages on the PCB and hold them theretemporarily until the soldering step is performed. According toconventional techniques, a screen with multiple holes is positionallyand carefully aligned with the PCB so that the screen holes aresuperimposed on the bonding sites on the PCB. Solder paste is thensquirted through the holes of the screen onto the bonding sites of thePCB. Solder paste is a conductive material which forms a temporary glue.

[0005] After the solder paste has been applied to the bonding sites, theIC packages are positioned atop the PCB. The solder paste temporarilyadheres the conductive leads of the IC package to the correspondingbonding sites. Solder is then applied to the bonding sites, and the PCBis subjected to ultraviolet light or other techniques for causing thesolder to melt and completely surround and secure the conductive leadsof the IC package to the bonding sites.

[0006] The use of solder paste for temporarily mounting IC packages ontoPCBs creates numerous problems. First, the process of positioning andaligning the screen over the PCB and squirting the solder paste throughthe screen holes is a difficult, time-consuming task. Second, the solderpaste is an extremely messy substance and can cause problems if notprecisely applied. Third, after the permanent solder is applied, thePCBs must be cleaned with special cleaning materials, such as freon-typecleaners, to remove all of the solder paste. Accordingly, the presentmounting technique introduces several additional manufacturing stepsthat reduce overall manufacturing efficiency while increasing costs.

[0007] The present invention eliminates the above-mentioned drawbacks byproviding a system and method for mounting integrated circuits ontoprinted circuit boards without the use of solder paste.

[0008] Another drawback in conventional manufacturing techniques isthat, when an IC package fails during the testing, it is often toodifficult to break the solder bonds and remove the defective IC packagewithout damaging the PCB or other components. Thus, the entiremanufactured board is discarded, even though most of the board and ICpackages are operative. This causes significant waste because otherwiseoperable components are needlessly thrown away.

[0009] The present invention provides a method for testing integratedcircuits and printed circuit boards prior to the soldering step. Thistesting method thereby permits removal of defective components withoutdiscarding the operable components.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

[0011]FIG. 1 is a top plan view of a portion of a PCB having an ICpackage mounted thereon. FIG. 1 also shows a partial cut away viewillustrating a semiconductor chip within the IC package.

[0012]FIG. 2 is an enlarged top plan view of the semiconductor chipshown in FIG. 1.

[0013]FIG. 3 shows a cross-sectional view taken along line 3-3 in FIG.1.

[0014]FIG. 4 is a diagrammatic illustration of a system and method formounting integrated circuits onto printed circuit boards according tothis invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] This disclosure of the invention is submitted in furtherance ofthe constitutional purposes of the U.S. Patent Laws “to promote theprogress of science and useful arts” (Article 1, Section 8).

[0016] According to one aspect, this invention encompasses a method formounting an integrated circuit (IC) device onto a printed circuit board(PCB), the PCB having a plurality of bonding sites provided thereon, theIC device having a plurality of conductive bonding portions forelectrically contacting corresponding bonding sites when the IC deviceis mounted to the PCB, the method comprising the following steps:

[0017] providing a PCB having an upper surface;

[0018] providing magnetic material within the IC device;

[0019] inducing a magnetic field of a selected strength at the surfaceof the PCB to hold the IC device onto the PCB; and

[0020] soldering the conductive bonding portions to the correspondingbonding sites of the PCB while the IC device is held onto the PCB by themagnetic field.

[0021] According to another aspect, this invention defines a system formounting an integrated circuit (IC) device onto a printed circuit board(PCB), the system comprising:

[0022] a PCB having a plurality of bonding sites and an upper surface;

[0023] an IC device having a plurality of conductive portions forelectrically contacting corresponding bonding sites when the IC deviceis mounted to the PCB, a portion of the IC device being formed of amagnetic material; and

[0024] field creating means for controllably inducing a magnetic fieldat the upper surface of the PCB, the magnetic field having a selectedstrength sufficient to hold the IC device onto the PCB.

[0025]FIG. 1 illustrates a portion of a printed circuit board (PCB) 10having an integrated circuit (IC) device 20 mounted thereon. PCB 10 hasmultiple conductive traces 12 formed in a selected pattern to buselectronic signals across the board to and from IC device 20. Conductivetraces 12 terminate on the surface of PCB 10 at bonding sites 13.

[0026] PCB 10 consists of multiple layers 14 a-14 c of insulativematerial such as paper bonded with phenolic resin or glass fibers bondedwith epoxy resin (FIG. 3). The circuitry pattern of conductive tracescan be provided on the upper surface of the PCB 10 (as shown in FIG. 1)or on intermediate layers as illustrated by traces 16 shown in FIG. 3.To access the circuitry provided on intermediate layers, “through-holes”are formed in the layers, as represented by through-hole 18. Conductivematerial fills through-hole 18 to join conductive traces 12 on the uppersurface of PCB 10 to conductive traces 16 provided on intermediate layer14 b of PCB 10. Traces 12 and 16 are formed of a conductive material,such as copper.

[0027] According to one aspect of this invention, PCB 10 includes alayer 19 of magnetic material interspersed between two layers of thelaminated PCB. Preferably, the magnetic material is a metal that iscapable of being magnetized. For instance, layer 19 is preferably formedof iron, nickel, cobalt, mixtures thereof, or other materials composedat least partially of these metals. Alternatively, as a less preferredapproach, the magnetic material has permanent magnet characteristics.This approach is less preferred because employing a permanent magneticmaterial may adversely affect normal operation of the PCB and IC devicesthereon. Layer 19 is discussed below in more detail.

[0028] IC device 20 is illustrated as an IC package consisting of asemiconductor integrated circuit chip 22, a plastic casing 24 whichencapsulates and protects IC chip 22, and a lead frame 28 which providesan electrical interconnection between IC chip 22 and traces 12 of PCB10. Lead frame 28 has multiple conductive leads 30 which protrude fromplastic casing 24 to electrically contact bonding sites 13 on PCB 10. Asshown in FIG. 3, the conductive leads are “J”-shaped which is common forsurface mounted IC packages.

[0029] IC device 20 is shown as an IC package for purposes ofexplanation. However, IC device 20 encompasses various other embodimentshaving IC chips and interconnecting bonding portions that contact thePCB bonding sites. For example, IC device 20 may consist of anunpackaged semiconductor integrated circuit chip having multipleconductive bonding pads (instead of leads) which mount directly tobonding sites on PCB 10. Additionally, the conductive leads need not be“J”-shaped, but can be straight (such as a dual in-line IC package) orhave other geometries.

[0030] According to an aspect of this invention, the semiconductor ICchip 22 has a layer of magnetic material. As above, the magneticmaterial is preferably a metal that is capable of being magnetized (suchas iron, nickel, or cobalt), or less preferably, a metal havingpermanent magnetic characteristics. As shown in the enlarged view ofFIG. 2, a layer of magnetic material 32 is provided on top of IC chip22. The layer of magnetic material is electrically isolated within theIC chip 22 by insulating materials that are within the purview of one ofordinary skill in the art. Here, layer 32 of magnetic material isspatially separated from pads 34 which are used to interconnect withlead frame 28. Although layer 32 is preferably provided on top of ICchip 22, layer 32 may be interwoven within the semiconductor structure.

[0031] According to another aspect of this invention, lead frame 28 isformed of a magnetic material.

[0032] According to this invention, IC devices are temporarily mountedonto PCBs using a magnetic coupling approach. With reference to FIG. 3,a magnetic field F of a selected strength is controllably induced orcreated by a field creating means at the upper surface of PCB 10. Thismagnetic field F attracts the magnetic material provided in IC device 20(such as in lead frame 28 or in layer 32 of IC chip 22). The magneticfield has sufficient strength to hold IC device 20 onto PCB 10 at leasttemporarily until conductive leads 30 can be soldered to correspondingbonding sites 13 of the PCB. As shown in FIG. 1, IC device 20 ispreferably held by the magnetic field in such a manner that conductiveleads 30 are aligned with corresponding bonding sites 13. The fieldstrength used to hold the ID devices onto the PCBs varies depending uponthe distance between the field creating means and the ID devices and anymaterial therebetween. More specifically, the magnetic field strength isinversely proportional to the distance between the ID devices and thePCBs.

[0033] According to one preferred embodiment of the field creatingmeans, layer 19 of magnetic material is magnetized to create magneticfield F. The magnetic field flows into the metal provided in IC device20 and turns the metal into a temporary magnet, whereby the magneticlayer 19 attracts the magnetic metal in IC device 20. According to analternative embodiment of the field creating means, magnetic field F canbe created by a magnetic source external to both PCB 10 and IC device20. For example, an electromagnet could be provided beneath PCB 10 toinduce a magnetic field of sufficient strength to hold IC device 20 ontoPCB 10. This alternative embodiment is particularly useful if PCB 10does not have a layer 19 of magnetic material which can be magnetized toattract IC device 20.

[0034]FIG. 4 diagrammatically illustrates a system for mounting an ICdevice onto a PCB. The system includes a mounting station 40, a testingstation 50, and a soldering station 60. PCBs 41, 51, and 61 are shown atrespective stations. The PCBs are moved in sequence through mountingstation 40, testing station 50, and soldering station 60 by a conveyormechanism, manually, or by some other apparatus. PCBs 41, 51, and 61have the same structure as discussed above with respect to PCB 10 inthat all three contain a layer of magnetic material. The layers ofmagnetic material within PCBs 41, 51, and 61 are selectively magnetizedand demagnetized by magnet control system 70. Magnet control system 70is electrically or magnetically coupled to the individual PCB layers ofmagnetic material, as is illustrated by intercoupling lines 72-74.According to this arrangement, magnetic control system 70 canindependently magnetize or demagnetize any one of the PCBs withoutsimilarly magnetizing or demagnetizing the remaining PCBs.

[0035] At mounting station 40, individual IC devices 20 are transferredor moved from a supply location 42 to PCB 41 using a transfer mechanism44. Transfer mechanism 44 preferably comprises a robotic arm 45 and acontroller 46. Robotic arm 45 has a handling instrument 48 provided atthe distal end thereof for contacting and handling individual IC devices20. According to this invention, the handling instrument has anelectromagnet provided therein with a relatively flat surface forcontacting and mating with the relatively flat upper surfaces of ICdevices 20. An electromagnet consists of a coil of wire wound around amagnetizable core, such as an iron core. When current flows through thecoil, it creates a magnetic field having a strength dependent upon theamount of current fed through the coil. When current is stopped, themagnetic field ceases. Controller 46 is coupled to selectively activateand deactivate the electromagnet provided in handling instrument 48.

[0036] In operation, robotic arm 45 positions handling instrument 48above an IC device 20 at supply location 42. Control system 46 activatesthe electromagnet in handling instrument 48 to induce a magnetic fieldwhich attracts and holds IC device 20 against the surface of handlinginstrument 48. Robotic arm 45 then moves IC device 20 to PCB 41 andaligns the conductive leads of IC device 20 with the correspondingbonding sites of PCB 41. Robotic arm 45 then places the conductive leadsin contact with the corresponding bonding sites. Next, controller 46deactivates the electromagnet in handling instrument 48 to eliminate themagnetic field and thereby release IC device 20 from handling instrument48.

[0037] Magnet control system 70 magnetizes the layer of magneticmaterial within PCB 41 to induce a magnetic field at the upper surfaceof PCB 41. The magnetic field has a selected strength effective to holdIC devices 20 onto PCB 41. PCB 42 is then transferred to testing station50, as represented by PCB 51, while the magnetic field is maintained.

[0038] At testing station 50, PCB 51 and IC devices 20 are tested todetermine whether the completed board has any defects. Accordingly,another aspect of this invention relates to a method for testing anintegrated circuit (IC) device and a printed circuit board (PCB), thePCB having a plurality of bonding sites provided thereon, the IC devicehaving a plurality of conductive bonding portions for electricallycontacting corresponding bonding sites when the IC device is mounted tothe PCB, the method comprising the following steps:

[0039] inducing a magnetic field at the bonding sites of the PCB;

[0040] magnetically holding the conductive bonding portions of the ICdevice in electrical contact with the corresponding bonding sites of thePCB using the magnetic field; and

[0041] testing the PCB and IC device while the IC device is being heldonto the PCB by the magnetic field.

[0042] Testing station 50 has a testing unit 52 which evaluates the PCBand IC devices while the IC devices 20 are held onto PCB 51 by amagnetic field. The magnetic field is maintained at the surface of PCB51 by magnet control system 70 from the time it was initiated atmounting station 40, during transfer from mounting station 40 to testingstation 50, and during the evaluation period at testing station 50. Testunit 52 includes a probe 54 having multiple prongs 58 for contacting theedge connector of PCB 51 and imparting test signals to PCB 51 and ICdevices 20, and a test controller 56 for controlling the testingpatterns sent to PCB 51 and evaluating the data returned therefrom.

[0043] If the board tests positively, PCB 51 is transferred to solderingstation 60, as represented by PCB 61, while the magnetic field ismaintained. On the other hand, if the board fails any testing protocol,the inoperative components are identified and removed from the board.

[0044] This method of testing is advantageous over prior art techniquesin that the IC devices 20 are temporarily held onto PCB 51 duringtesting by a magnetic coupling. The IC devices 20 have not yet beenpermanently soldered to the PCB. Accordingly, if a defect is discoveredin one of the IC devices or in the PCB, the defective component can beremoved and the remaining components recaptured for later use on otherboards. This effectively eliminates the needless waste of discardingotherwise operable components that commonly occurs under conventionalmanufacturing and testing procedures.

[0045] According to another aspect, the invention also encompasses amethod for testing a die wherein the die has circuitry provided on asemiconductor substrate. The method comprises the following steps: (1)magnetically holding the die in a selected orientation; (2) applying atesting device (such as a probe or test prongs) to the die; and (3)evaluating the die to determine whether the die is defective. Theevaluation step might consist of transferring test data to and from thedie through the testing device to ascertain whether the die is properlyprocessing or storing the data.

[0046] At soldering station 60, a soldering unit 62 solders theconductive leads of IC devices 20 to corresponding bonding sites on PCB61 while IC device 20 is held onto PCB 61 by a magnetic field. Solderingunit 62 comprises a solder applicator 64 and a solder controller 66.Magnetic control system 70 maintains the magnetic field at the surfaceof PCB 61 during its transfer from testing station 50 and at least theinitial soldering process until the IC device is adequately secured toPCB 61. Thereafter, magnetic control system 70 ceases to create amagnetic field at the surface of PCB 61.

[0047] The above-preferred system includes a field creating means thatinduces a magnetic field at the surface of the PCBs by magnetizinglayers of magnetic material provided within the PCBs. Alternatively, forPCBs that are constructed without these layers, the field creating meanscould consist of electromagnets are provided beneath the PCBs toselectively create a magnetic field, or cease to create a magneticfield, at the surface of the PCBs. In this alternative embodiment,magnet controller 70 would interface with such electromagnets to provideselective control of the magnetic fields. The electromagnets would beassigned to individual PCBs and carried with them through the variousstations to insure that a magnetic field is maintained at mountingstation 40, testing station 50, and soldering station 60.

[0048] The above process is provided in its preferred sequence ofoperation. However, certain steps may be conducted in a different orderthan described. For example, at mounting station 40, the magnetic fieldcreated by magnet control system 70 may be generated prior todeactivating the magnetic field induced by the electromagnet in handlinginstrument 48.

[0049] This invention is advantageous over prior art mounting techniques11 in that it eliminates the use of solder paste. Accordingly, theinefficient steps of positioning and aligning a screen and then applyingsoldering paste to the many bonding sites on the PCB are eliminated.Additionally, the mess associated with the application and cleaning ofsolder paste is also eliminated.

[0050] In compliance with the statute, the invention has been describedin language more or less specific as to structural and methodicalfeatures. It is to be understood, however, that the invention is notlimited to the specific features described and shown, since the meansherein disclosed comprise preferred forms of putting the invention intoeffect. The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

claims:
 1. A method for mounting an integrated circuit (IC) device ontoa printed circuit board (PCB), the PCB having a plurality of bondingsites provided thereon, the IC device having a plurality of conductivebonding portions for electrically contacting corresponding bonding siteswhen the IC device is mounted to the PCB, the method comprising thefollowing steps: providing a PCB having an upper surface; providingmagnetic material within the IC device; inducing a magnetic field of aselected strength at the surface of the PCB to hold the IC device ontothe PCB in such a manner that the conductive portions of the IC deviceare in alignment with the corresponding bonding sites; and soldering theconductive bonding portions to the corresponding bonding sites of thePCB while the IC device is held onto the PCB by the magnetic field.
 2. Amethod for mounting an integrated circuit (IC) device onto a printedcircuit board (PCB) according to claim 1 wherein: the IC devicecomprises a semiconductor integrated circuit chip having a plurality ofconductive bonding pads which form the conductive bonding portions; andthe method further comprising providing a layer of magnetic materialwithin the semiconductor integrated circuit chip.
 3. A method formounting an integrated circuit (IC) device onto a printed circuit board(PCB) according to claim 1 wherein: the IC device comprises an ICpackage consisting of a semiconductor integrated circuit chipencapsulated in a casing and a lead frame electrically coupled to thesemiconductor integrated circuit chip, the lead frame having a pluralityof conductive leads which form the conductive bonding portions; and theprocess further comprising forming the lead frame of a magneticmaterial.
 4. A method for mounting an integrated circuit (IC) deviceonto a printed circuit board (PCB) according to claim 1 wherein themagnetic material is selected from a group consisting of iron, nickel,and cobalt.
 5. A method for mounting an integrated circuit (IC) deviceonto a printed circuit board (PCB) according to claim 1 furthercomprising: prior to the soldering step, testing the PCB and IC devicewhile the IC device is being held onto the PCB by the magnetic field. 6.A method for mounting an integrated circuit (IC) device onto a printedcircuit board (PCB) according to claim 1 further comprising: providing alayer of magnetic material in the PCB; and magnetically charging the PCBlayer to attract the magnetic material in the IC device and to hold theIC device onto the PCB.
 7. A method for mounting an integrated circuit(IC) device onto a printed circuit board (PCB), the PCB having aplurality of bonding sites provided thereon, the IC device having aplurality of conductive bonding portions for electrically contactingcorresponding bonding sites when the IC device is mounted to the PCB,the method comprising the following steps: providing a PCB having anupper surface; providing magnetic material within the IC device; movingthe IC device to the PCB; aligning the conductive portions of the ICdevice with the corresponding bonding sites of the PCB; placing theconductive portions in contact with the corresponding bonding sites;inducing a magnetic field of a selected strength at the surface of thePCB to hold the IC device onto the PCB; and soldering the conductiveportions to the corresponding bonding sites of the PCB while the ICdevice is held onto the PCB by the magnetic field.
 8. A method formounting an integrated circuit (IC) device onto a printed circuit board(PCB) according to claim 7 wherein: the IC device comprises asemiconductor integrated circuit chip having a plurality of bonding padswhich form the conductive bonding portions; and the method furthercomprising providing a layer of magnetic material within thesemiconductor integrated circuit chip.
 9. A method for mounting anintegrated circuit (IC) device onto a printed circuit board (PCB)according to claim 7 wherein: the IC device comprises an IC packageconsisting of a semiconductor integrated circuit chip encapsulated in acasing and a lead frame electrically coupled to the semiconductorintegrated circuit chip, the lead frame having a plurality of conductiveleads which form the conductive bonding portions; and the processfurther comprising forming the lead frame of a magnetic material.
 10. Amethod for mounting an integrated circuit (IC) device onto a printedcircuit board (PCB) according to claim 7 further comprising: prior tothe soldering step, testing the PCB and IC device while the IC device isbeing held onto the PCB by the magnetic field.
 11. A method for mountingan integrated circuit (IC) device onto a printed circuit board (PCB)according to claim 7 further comprising: providing a layer of magneticmaterial in the PCB; and magnetically charging the PCB layer to attractthe magnetic material in the IC device and to hold the IC device ontothe PCB.
 12. A method for mounting an integrated circuit (IC) deviceonto a printed circuit board (PCB) according to claim 7 furthercomprising: moving the IC device using a transfer mechanism having ahandling instrument, the handling instrument having a surface; creatinga magnetic field to attract the IC device to the surface of the handlinginstrument; maintaining the magnetic field to transfer the IC device tothe PCB and to align the conductive portions with the bonding sites; andceasing to create the magnetic field after the conductive portions arealigned with the bonding sites.
 13. A method for mounting an integratedcircuit (IC) device onto a printed circuit board (PCB) according toclaim 7 further comprising: providing a layer of magnetic material inthe PCB; moving the IC device using a transfer mechanism having ahandling instrument, the handling instrument having a surface; creatinga magnetic field to attract the IC device to the surface of the handlinginstrument; maintaining the magnetic field to transfer the IC device tothe PCB and to align the conductive portions with the bonding sites;ceasing to create the magnetic field after the conductive portions arealigned with the bonding sites; and magnetically charging the PCB layerto attract the magnetic material in the IC device and to hold the ICdevice onto the PCB.
 14. A system for mounting an integrated circuit(IC) device onto a printed circuit board (PCB), the system comprising: aPCB having a plurality of bonding sites and an upper surface; an ICdevice having a plurality of conductive portions for electricallycontacting corresponding bonding sites when the IC device is mounted tothe PCB, a portion of the IC device being formed of a magnetic material;and field creating means for controllably inducing a magnetic field atthe upper surface of the PCB, the magnetic field having a selectedstrength sufficient to attract the magnetic material provided in the ICdevice and to hold the IC device onto the PCB.
 15. A system for mountingan integrated circuit (IC) device onto a printed circuity board (PCB)according to claim 14 wherein: the IC device comprises a semiconductorintegrated circuit chip having a plurality of conductive bonding padswhich form the conductive bonding portions; and the magnetic material isprovided as a layer in the semiconductor integrated circuit chip, thelayer of magnetic material being electrically isolated within thesemiconductor integrated circuit chip.
 16. A system for mounting anintegrated circuit (IC) device onto a printed circuity board (PCB)according to claim 14 wherein: the IC device comprises a semiconductorintegrated circuit chip encapsulated within a casing and a lead frameelectrically coupled to the semiconductor integrated circuit chip, thelead frame having a plurality of conductive leads which form theconductive portions; and the lead frame has the magnetic materialprovided therein.
 17. A system for mounting an integrated circuit (IC)device onto a printed circuity board (PCB) according to claim 14wherein: the PCB includes a layer of magnetic material; and the fieldcreating means comprises a magnet control system for magnetizing themagnetic material in the PCB to attract the IC device to the surface ofthe PCB.
 18. A system for mounting an integrated circuit (IC) deviceonto a printed circuity board (PCB) according to claim 14 wherein: thefield creating means comprises an electromagnet positioned beneath thePCB to induce a magnetic field at the surface of the PCB.
 19. A systemfor mounting an integrated circuit (IC) device onto a printed circuityboard (PCB) according to claim 14 wherein: the bonding sites comprisebonding pads provided on the surface of the PCB; and the conductiveportions of the IC device comprise “J”-shaped leads.
 20. A system formounting an integrated circuit (IC) device onto a printed circuit board(PCB) according to claim 14 further comprising a soldering unit forsoldering the conductive portions to the bonding sites on the PCB whilethe IC device is held onto the PCB by the magnetic field induced by thefield creating means.
 21. A system for mounting an integrated circuit(IC) device onto a printed circuit board (PCB) according to claim 14further comprising a testing unit for evaluating the PCB and IC devicewhile the IC device is held onto the PCB by the magnetic field inducedby the field creating means.
 22. A system for mounting an integratedcircuit (IC) device onto a printed circuit board (PCB) according toclaim 14 further comprising: a transfer mechanism for transporting theIC device to the surface of the. PCB, the transfer device having ahandling instrument, the handling instrument having an electromagnet foralternately magnetizing and ceasing to magnetize the handlinginstrument; a control system coupled to selectively activate anddeactivate the electromagnet; the handling instrument attracting andholding the IC device when the electromagnet is activated by the controlsystem to magnetize the handling instrument; and the handling instrumentreleasing the IC device when the electromagnet is deactivated by thecontrol system to cease to magnetize the handling instrument.
 23. Amethod for testing an integrated circuit (IC) device and a printedcircuit board (PCB), the PCB having a plurality of bonding sitesprovided thereon, the IC device having a plurality of conductive bondingportions for electrically contacting corresponding bonding sites whenthe IC device is mounted to the PCB, the method comprising the followingsteps: inducing a magnetic field at the bonding sites of the PCB;magnetically holding the conductive bonding portions of the IC device inelectrical contact with the corresponding bonding sites of the PCB usingthe magnetic field; and testing the PCB and IC device while the ICdevice is being held onto the PCB by the magnetic field.
 24. A methodfor testing a die, the die having circuitry provided on a semiconductorsubstrate, the method comprising the following steps: magneticallyholding the die in a selected orientation; applying a testing device tothe die; and evaluating the die to determine whether the die isdefective.